You are NOT paranoid. I have the same problem. What you have is most likely Premature Atrial Contractions (PAC's) or Premature Ventrical Contractions (PVC's) which feels like your heart stops for a second (it doesn't stop!). When you burb, some acid can come up your esophagus
and as it irritates the lining of the esophagus, it stimulates the vagal nerve
, which in turn stimulates the heart, making it have PAC (Most likely) or PVC (less likely). Get checked for reflux (even if you don't feel heart burn).